Shoulder bumping technique

[LaHunter]

I'm new to reloading and would like some advice on shoulder bumping. What I'm noticing is that on the first pass through my FL sizing die the case lengthens of course, and after a couple more strokes the shoulder is back about a half of a thousandth (or not at all), and sometimes further passes will get me about 0.0015 or maybe 0.002, which is what I'm trying to obtain. Adjusting the die less than a tenth of a turn deeper gets me too far, sometimes 0.0035 or more. I can't seem to find the middle ground that gets me 1.2-2 thousandths on the first pass. First time the ram comes down (full stroke) there is a gap between the die and shell holder about the size of a sheet of paper, and second or third the die touches. With no case, the die touches. Appropriate "cam-over" at the end of the stroke. I attribute what I'm seeing to some slop in the press, not sure if I should change anything.

What would you do? Does it sound like I need to work on getting better adjustment or is this acceptable technique?

Equipment:
RCBS Summit press, bolted solidly
RCBS FL sizing dies & shellholder
Measuring shoulder with Larry Willis digital headspace gauge (confirmed my technique with them, measurements are consistent and repeatable)
Norma 6.5 Creedmoor brass, once fired, deprimed and cleaned, lubed

Redding Competition Shell Holder set.

 

[Apnea]

Thank you all for taking the time to respond. Lots that I didn't know. Some improvement today after using more lube and making sure to get the case all the way to the head. Removed some slop from the press by replacing the two bolts with a single 3/8" bolt, and focusing on getting the cases only back to original shoulder (after firing) or +0.001 (no bolt resistance). Still a little variation there but the floating target explanation makes sense. I'll try to digest more of this tomorrow.

Once again thanks for explaining. Looks like more stuff to buy....

 

[338 dude]

And it begins!

Where is Eric Cortina?

 

[Will Gray]

Or you could just grind .002" of the die base and full length resize as usual. What is wrong with this idea?

 

[Chase723]

Here's some more food for thought. The video that Broz made is excellent, but one thing you'll notice is that if your sizing is right on the cusp then you'll have a couple where the bolt close will still have a little bit of shoulder feel because for whatever reason the brass has just a tiny little bit of spring back. Alex Wheeler suggests once you get to where the bolt will close without any resistance bump it back another 2 thou...or just a little bit more. He thinks that it allows the bullet to align more concentrically with the bore upon firing and obviously every round will chamber. I'm starting to believe this is true. He also holds like 20 something records so I'm inclined to believe that his experience is a little more than anecdotal.

 

[jimbires]

Or you could just grind .002" of the die base and full length resize as usual. What is wrong with this idea?

he can over sizes his brass now . removing a little off the bottom of the die will allow him to over size his brass even more . cutting the die , would not help the problem of inconsistent sizing .

 

[338 dude]

Don't feel like it has to be .002" like many say. I have heard of br guys using up to .006" since the primer pocket gives out before the case neck and shoulder from work. Point is, consistency is key (capt obvious). Set your dies close to .002", or .004". Just pick and run. If you can't anneal. .004" ish will help later since there will be more spring back thus Tighter fit. Flame suit on

I actually try to have .001 headspace I have never once had a case failure of any kind in over five years I've never had a stuck case and like said I believe no matter what you do as far as amount consistency is key And I always set up my dies for minimal sizing and use a bushing that does minimal sizing only what is necessary

 

[338 dude]

Or you could just grind .002" of the die base and full length resize as usual. What is wrong with this idea?

As I've mentioned in the past why screw up a die when a shell holder is switched out so quickly and cheaply it just doesn't make sense to me Try a different brand of shell holder or grind the shell holder

 

[Mram10us]

Or you could just grind .002" of the die base and full length resize as usual. What is wrong with this idea?

I have done this, then decided to shave the shell holder on the lathe. Not saying one is better since they both led to the same result. I shave the shell holder because I have two I use most of the time and it saves having to shave lots of dies.

 

[25WSM]

Try imperial sizing die wax. Works great and the little can last along time. Let your brass sit in the die at least 5 seconds will help with your consistency. An no your die does not have to be cammed over to get consistent results. I don't let any die touch my shell holder. If it does I cut a little off the bottom of it. I always go for at least . 003 bump to make sure all my brass fit easily.. 002 will work if your brass is annealed often. I only anneal every other shot so I do the
. 003 just to be safe.
Shep

 

[jimbires]

I " THINK " a lot of the reason competition shooters like a little more clearance is they can cycle the bolt and not disturb the rifle setting on the bags as much . also they don't want to chance a tight fitting piece of brass during an event . the rifle moves on the bags , conditions change , now the next couple go out of the group .

 

[Scott E Ames]

Just started adding Redding S bushing dies to my reloading. Can shoulders be bumped back with these dies? Can you bump a shoulder back with the fixed neck sizer dies in a Redding 3 die set or will I need to add a "body" die to all of my S bushing die sets?

 

[338 dude]

Just started adding Redding S bushing dies to my reloading. Can shoulders be bumped back with these dies? Can you bump a shoulder back with the fixed neck sizer dies in a Redding 3 die set or will I need to add a "body" die to all of my S bushing die sets?

My Redding set t is a three die set with a separate body die for bumping

 

[jimbires]

here is how easy sizing brass for a rifle can be . no turning of the die needed when loading for a different rifle of the same cartridge . I have three different 7mm-08's . a Tikka , a Remington , and a browning . I just need to use the correct shellholder . I also use these shellholders for my 260 rem . I'll say it again , I could never get consistent shoulder bump without the die contacting the shellholder .